The present invention is generally related to data storage and specifically to a system and method for partitioning a storage area network associated data library.
One of the most attractive aspects of a storage area network (SAN) is that network connectivity enables a company to efficiently use storage by sharing storage capacity among a number of servers. This may be implemented using a large number of small capacity storage devices. However, unless sufficiently robust management software is employed, such use of small capacity devices in a SAN may result in significant management overhead.
Most users prefer to install large capacity storage device(s) and partition the device(s), assigning each partition to a different server. For example, existing firmware for enterprise level disk arrays allow users to define multiple redundant array of independent disks (RAID) sets, where each RAID set appears as a different logical unit number (LUN). Each one of these LUNs may be dedicated to a different server. However, to-date special hardware, as described below, or special backup software has been used to implement partitioning.
An existing hardware-based partitioning scheme for existing libraries is known as shared library services. This implementation requires at least one bridge, sometimes referred to as a quad interface processor, to be placed between the drives and the library controller. The host side of each quad interface processor consists of two small computer systems interface (SCSI) buses, and the quad interface processor may show a single virtual library controller, with its own SCSI ID, on each SCSI bus. Thus there may be one virtual library per host SCSI bus, containing the virtual library controller and the drives in that partition. Each partition of such an existing library may have slots added in increments and drives may be added individually or in pairs. Each internal SCSI bus in this existing partitioning scheme may accommodate up to two drives; drives on the same bus must be in the same partition.
Such an existing hardware-based library partitioning scheme may use switches to provide secure partitioning. Existing quad interface processor bridges employ a SCSI target ID for each partition. Each SCSI ID may have a separate SCSI/fiber channel (FC) bridge associated with it. Other existing libraries do not provide secure partitioning.
Existing software-based partitioning solutions typically employ a host system that restricts access to portions of a tape library. The host restrictions are implemented by a mediating (software) process on a host system to enforce partition restrictions. However, this approach is problematic. Specifically, the approach is undesirable if the tape library is utilized in a storage service provider (SSP) environment. In SSP environments, the tape library and the host systems belong to different entities (e.g., the SSP and the customers). Placement of software mediating processes on host systems is unattractive, because it increases the burden on the customers to make use of the storage service. Also, corporate environments impose relatively long qualification cycles for new host system software. New software is typically only introduced in such environments once every six to eight months due to qualification cycles. Moreover, many customers are unwilling to allow other parties to place software on their host systems. Additionally, the software mediating process approach is typically incompatible with existing data back-up utilities, i.e., the software mediating process approach requires the use of specialized data back-up applications. Hence, users are effectively denied the ability to run desired backup software.
A storage area network associated data library partitioning system comprises a plurality of storage element slots adapted to store data storage media, at least one set of at least one of the slots is assigned to one partition of a plurality of partitions, a plurality of data transfer elements that are adapted to receive the media and transfer data to and from the media, each of at least one set of at least one of the data transfer elements is assigned to one of the partitions, and a library controller that assigns a different logical element designation to a virtual controller for each of the partitions, the virtual controllers directing movement of the media to and from one of the set of slots assigned to a same of the partitions.
A method in accordance with the present invention for partitioning a storage area network associated data library comprises assigning a different logical element designation to each of a plurality of library partitions, establishing the partitions in the data library, each of the partitions comprising at least one storage element slot and at least one data transfer element, each of the slots adapted to store media, and each of the data transfer elements adapted to receive the media and transfer data to and from the media, and controlling movement of the media to and from the slots assigned to a same partition.